Research On Matching Law Of The Front Cylinder And The Rear Cylinder Of The Engine With Charge Transit Between Different Cylinders

For improving fuel economy, a few innovation internal combustion engines havebeen developed in recent years, which have a common characteristic: charge transitbetween cylinders. It is of great significance in developing innovation engines thatstudying the principle of energy saving, mastering the matching law of the frontcylinder and the rear cylinder of the engine and predicting energy-saving effect of thiskind engine.A conventional4-cylinder4-stroke gasoline internal combustion engine istransformed into an innovative “4+4” stroke engine with the technology of chargetransit between different cylinders. Simulation models for “4+4” stroke engine havebeen built through1-D simulation software GT-Power and the accuracy of models isverified. Three issues is involved for matching law of the front cylinder and the rearcylinder of the engine with charge transit between different cylinders: valve timing,mainly including the influence of the exhaust advance angle of the front cylinder andthe intake advance angle of the rear cylinder on torque, break specific fuel consumptionand pressure of the transfer tube; the influence of volume ratio on torque and breakspecific fuel consumption; the optimal matching of transfer pipe, including the lengthand diameter of transfer pipe and the volume of the pressure stabilizing cavity.The study shows: the exhaust advance angle of the front cylinder and the intakeadvance angle of the rear cylinder influence the power performance and fuel economyof engines through the pressure of the transfer tube mainly; the exhaust advance angleof the front cylinder has a more significant influence compared with the intake advanceangle of the rear cylinder; the exhaust advance angle of the front cylinder for maximumtorque and minimum specific fuel consumption doesn’t change essentially while theintake advance angle of the rear cylinder decreases with increasing speed. In part loadthe volume ratio for the lowest fuel consumption increases with torque augmenting andbarely changes with the change of speed. For the external characteristic, there is anoptimal volume ratio for maximum torque and another optimal volume ratio forminimum BSFC. Moreover, both of the optimal volume ratios decrease with theincrease of the engine speed. Maximum torque and minimum specific fuel consumption can be obtained when volume ratio is equal to1with speed above4000r/min. Thetorque increases and the break specific fuel consumption decreases with the length oftransfer tube increasing; the torque decreases and the break specific fuel consumptionincreases with the diameter of transfer tube increasing. But the effect of the transfer tubediameter is not best when it is smallest, the diameter of exhaust valve is needed toconsider; the pressure stabilizing cavity has a small impact on internal combustionengine of charge transit between different cylinders.After optimizing the valve timing, volume ratios between former and latercylinders and cylinders transfer tube, the fuel economy of the engine with “4+4” strokehas been enhanced obviously. Comparing with the original engine, the average fuelconsumption decreases by5%. The engine with “4+2” stroke is studied also. The fuelconsumption of the optimized engine with “4+2” stroke decreases by more than20%inlow load and by more than10%in high load.